The physical proximity of a versatile medical cyclotron, modern radiochemistry laboratories and an appropriate positron-emission tomographic device (PET) form a nucleus for diverse neuroscience investigations. In this proposal, the result of combined efforts of the University of Miami Medical School, and the Mount Sinai Medical Center, we have described studies of ammonia, short-chain fatty acids, glucose and oxygen metabolism, measurements of local cerebral blood flow, platelet function and neurotransmitter chemistry and transmitter binding site localization. With the use of the core facility, we will study a variety of clinical conditions including hepatic encephalopathy, stroke, platelet disorders such as TTP, epilepsy, Parkinson's Disease and affective disorders. The quantitative data obtained from the study of illnesses in humans obviates the need to use imperfect models of disease and promises to lead to significant advances in our understanding of cerebral metabolism and function.